This invention relates to the production of metal strips and, more particularly, to the production of metal strips suitable for use in the coils of power transformers.
Power transformers, such as overhead distribution transformers and pad mounted distribution transformers, generally include coils which are wound from relatively wide strips of aluminum. In order to provide the requisite electrical characteristics for such transformers, it is necessary that the aluminum strips not only have accurate dimensions, but also have other desired characteristics, such as a desired electrical conductivity and 0-temper.
Heretofore, the aluminum strips have been produced by first casting aluminum into ingots and then cold rolling and hot rolling the ingots to form sheets which are then slit to form the strips. In addition, the strips have been subjected to secondary metal treating processes to contour the edges thereof. Contoured edges enable the strips to be insulated with a dielectric in an optimal manner.
While the foregoing processing has produced satisfactory strips, because of the number of steps involved, it is relatively costly. Accordingly, a continuous process minimizing the number of discreet steps is desirable. In this connection, consideration has been given to conventional extrusion processes. However, such conventional extrusion does not permit the continuous processing that is desired in connection with the production of flat metal strips for power transformer coils.